Origin

English has three main words scale, two of which share an ancestry. The scale of fishes and reptiles has the same root as the scale used for weighing, and both are related to shell. The first scale is the one in the scales fall from someone's eyes, ‘someone is no longer deceived’. In the biblical Acts of the Apostles the expression describes how St Paul, blinded by his vision on the road to Damascus, was given his sight back by God. The weighing scale had the early sense ‘drinking cup’(a meaning which survives in South African English) which probably transferred to the pans of the scales. It comes from Old Norse skál ‘bowl’, also source of the drinking toast skol. The scale in music and measuring derives from Latin scala ‘ladder’, from the root of scandere ‘to climb’, an element in ascend, descend, and condescend, all Late Middle English. See also echelon, scan